An extremely sensititive radioimmunoassay (RIA) for both myelin basic protein (BP) and proteolipid protein (PLP) has been developed. We are currently engaged in measuring the concentration of these proteins in normal, plaque and periplaque areas of multiple sclerosis patients and the presence of BP and PLP in serum and cerebrospinal fluid. A method for the isolation ofhomogeneous preparations of myelin proteins after coupling with 2-methoxy-2-4 diphenyl-3(2h) furanone (MDPF) has been developed. Myelin proteins coupled to MDPF are extremely fluorescent when riewed under ultraviolet light and the fluorescence is retained for twelve months. Therefore, it will be feasible to isolate pure preparatons of mylelin PLP and DM-20 after coupling with MDPF and repeated cycling by discontinuous and ccntinuous sodium dodecyl sulfate (SDS) gel systems. We will then explore the possibility that MDPF-labelled PLP or DM-20 will generate antibodies. This technique will be used to isolate pure preparations of PLP from light and heavy myelin in order to study the rate of synthesis and degradation of this protein in adult mouse brain.